Are you a previous patient of this hospital that you will be attending as your files will tell the tale!
You need to find an advocate. What hospital are you attending? On their website do they have a patients rights area that you can navigate through?
https://www.health.nsw.gov.au/patientconcerns/Pages/your-health-rights-responsibilities.aspxI think you are in NSW hence the link above, not sure it will help or not
There are patient advocates but I think from the little I have read so far that they are private, you need to engage and pay!
Who referred you to this procedure? Surely they can advocate for you and to answer your question
Do I stick to my guns the day before, and demand they put in the lines under sedation,Yes get your referring Dr to weigh on and bat for you
Best wishes